Characters are a *****.
Plot is easy. I could sit here right now and make up a great story. But the characters are what make a story worth taking the time to watch, read, listen to, etc. And characters are hard. They've got to be true, meaning that the story arc occurs naturally as a result of who they are. If you force a story point, you're comprising. With PR, there was lots of compromise.
First, there's just a simple matter of screentime. Very few minutes for lots of characters.
Second, the footage forces you to shove square pegs into round holes, sometimes.
Third, the schedule doesn't allow you to mull your options too long. You've got to move it pretty quickly.
And lastly, the main characters can't develop toooo much since they have to last the entire season. Therefore, some of my favorite characters are the ones who only come in for an episode or two. These are the ones that can come in with a flaw/problem, and then have it solved over the course of 22 mins. That can give the story a dimension other eps lack.
I never considered myself to be strong on character, though I have great respect for those who are. When I see a movie with great characters, I am awed and inspired. They work with the plot seamlessly. In fact, the plot and characters are reflections of the same element, or your story fails.